HISTOMORPHOLOGY OF THE DIGESTIVE-TRACT OF CHONOPELTIS-AUSTRALIS (CRUSTACEA, BRANCHIURA)

The morphology and histology of the digestive tract of the branchiuran crustacean, Chonopeltis australis Boxshall, 1976 are described from s erial sections. The foregut is differentiated into a preoral cavity, c ontaining the mandibles and tongue, an ascending oesophagus, with an H -shaped lumen invested with longitudinal, circular and dilator muscles , a horizontal oesophagus with a star-shaped lumen and lacking longitu dinal and dilator muscles, and an oesophageal funnel consisting of inn er and recurrent walls. The midgut is differentiated into anterior and posterior chambers, separated by an S-shaped muscular tube. The arbor escent midgut glands open laterally into the anterior part of the ante rior midgut. Columnar epithelial cells line the anterior midgut wherea s tall, papilliform cells are present in the epithelium of the posteri or midgut. The transition from posterior midgut to hindgut is marked b y the presence of very tall epithelial cells. The terminology describi ng the various parts of the digestive tract of branchiurans is discuss ed.